This application is related to Japanese Patent Application No. 2000-196546 filed on Jun. 29, 2000, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an inside/outside air switching device using a rotary door. More particularly, the present invention relates to a structure for preventing a freeze lock of the rotary door due to rainwater introduced from an outside of the inside/outside air switching device.
2. Description of Related Art
In a conventional inside/outside air switching device of a vehicle air conditioner described in JP-A-9-188124, a rotary door 113 shown in FIG. 6 is used for opening and closing inside and outside air introduction ports. That is, as shown in FIG. 6, the rotary door 113 includes a rotation shaft 113c, a circumference wall 113a provided at an upper side of the rotation shaft 113c to extend in a rotational direction of the rotary door 113, both fan-like side plates 113b connecting the rotation shaft 113c and the circumference wall 113a at both sides in an axial direction of the rotation shaft 113c, and protrusion walls 113d, 113e protruding toward outside from outer peripheral portions of the circumference wall 113a and the side plates 113b. In addition, packing members 114, 115 are provided on face and back surfaces of the protrusion walls 113d, 113e, respectively.
However, in the rotary door 113, the rotation shaft 113c is provided at a lower side of the circumference wall 113a through the fan-like side plates 113b, and seal surfaces of an inside/outside air switching box are tilted downwardly toward the rotation shaft 113c to contact the packing member 115. Accordingly, rainwater introduced from the outside air introduction port readily stays between the seal surfaces of the inside/outside air switching box and lower parts of the packing member 115 proximate to the rotation shaft 113c. Thus, the rotary door 113 may be frozen in a cold season due to rainwater.
In view of the foregoing problems, it is an object of the present invention to provide an inside/outside air switching device with a rotary door, which prevents a freeze of the rotary door due to rainwater.
According to the present invention, in an inside/outside air switching device, a rotary door for selectively opening and closing an inside air introduction port and an outside air introduction port includes a rotation shaft disposed rotatably, a circumference wall provided at an upper side of the rotation shaft to extend in a rotation direction, both fan-like side plates connecting the circumference wall and the rotation shaft at both sides in an axial direction of the rotation shaft, a protrusion wall provided along an entire periphery of the circumference wall and the side plates to protrude an outside of the rotary door, and a packing member made of an elastic member, and provided at both surface sides of the protrusion wall. An inside/outside air switching case has seal surfaces provided around both the ports to contact the packing member, at least one of both the first and second ports has a circumference opening provided to opposite to the circumference wall, and the rotary door is disposed in the case to form a clearance between the protrusion wall around a lower side of the rotation shaft and the seal surface. In addition, the clearance has a size equal to or larger than a predetermined dimension for preventing a water storage in the clearance. Accordingly, it can prevent rainwater from staying in the clearance, and it can prevent a freeze of the rotary door due to rainwater.
The rotation shaft is disposed at the lowest position in the rotary door. In this case, rainwater introduced from the outside air introduction port readily stays in the clearance lower than the rotation shaft. However, in the present invention, the clearance has a size equal to or larger than the predetermined dimension, rainwater introduced into the clearance readily flows downwardly.
Preferably, the packing member is separated around the lower side of the rotation shaft, and the clearance is defined at least by the protrusion wall on the lower side of the rotation shaft and the seal surface. Therefore, regardless a rotation position of the rotary door, rainwater introduced from the outside air introduction port moves along the side plates and the seal surface, and it can accurately prevent rainwater from staying under the rotation shaft.
Preferably, the seal surface for defining the clearance has a taper portion tilted downwardly in the case, at a position around the lower side of the rotation shaft. Therefore, rainwater introduced into the clearance can be effectively discharged downwardly, and it can effectively prevent a freeze of the rotary door due to rainwater.